carbon steel plate of 5 mm 3/16 inch minimum thickness, conforming to ASTM
A 36/A 36M. The inner casing shall be of welded construction, gastight and
watertight, designed for a transient condition (80 percent of yield
strength) at internal pressures of at least plus 4980 and minus 7470 Pa
plus 20 and minus 30 inches water gage. Joints shall be sealed by
continuous fillet or continuous complete penetration groove welds, as
applicable. The tube sheet opening arrangement and bag clearance shall
limit gas velocity between the bags at any point within the module to not
more than 1.27 m/s 250 ft/min at design conditions. Bag to wall clearance
used in calculating gas velocity shall not exceed bag to bag clearance.
Minimum bag clearance shall be 50 mm 2 inches. Additional space shall be
provided between rows of bags, as necessary, to clear access door supports
crossing the tube sheet. Tube sheet shall be continuous fillet or
continuous complete penetration groove welded gastight so that all flue gas
must pass through the bags. No caulking or sealing materials shall be
used. Tube sheet shall be arranged for individual top bag and cage removal
and reinforced, as required for pedestrian traffic (minimum support shall be
488 kg per square meter 100 pounds per square foot). Modules shall have
shop insulated, double-cased lift-off doors with quick-opening handles for
access to the tube sheet. Doors shall have high-temperature gaskets to
prevent air infiltration. Multiple tube sheet access doors shall be
provided such that each door shall be easily removable by two men. The
doors shall be provided with lifting handles. Top surface of access doors
shall be 6 mm 1/4 inch thick ASTM A 36/A 36M four-way raised pattern floor
plate. The manufacturer's standard tube sheet access door arrangement and
design will be considered provided the design provides adequate insulation
and protection against infiltration. The bag cleaning system shall be
designed to ensure efficient cleaning operation with a minimum pressure
drop across the system and with the gentlest possible cleaning mechanism to
ensure long bag life. Source of compressed air is specified under Section
[_____] COMPRESSED AIR SYSTEMS. Compressed air used in the cleaning system
shall pass through a dryer/filter system. The dryer shall be provided to
remove moisture from compressed air used in system. Dryer shall remove
sufficient moisture to provide a maximum dewpoint of [_____] degree C at
690 kpa (gage) degree F at 100 psig. A filter system shall be provided to
clean compressed air used in system. Filter system shall remove a minimum
of 90 percent to 95 percent of particles greater than 0.6 microns in
diameter. Filters shall be sized to operate for 90 days without service
under normal operating conditions and shall be easily accessible for
inspection and service. Dryer/filter system shall be sized service.
Dryer/filter system shall be sized for 120 percent of design air flow.
Dewpoint should be 6 degrees C 10 degree F lower than design minimum
temperature. In no case should a dewpoint be greater than 2 degrees C 35
degrees F. Each module shall have a factory-installed compressed air
header, pulse valves, and distribution piping. Valves and wiring shall be
located in a weather protected enclosure with forced air ventilation to
prevent freezing or overheating. The enclosure shall be readily accessible
through hinged doors. Diaphragm valves shall be factory prewired to a
junction box. Entire pulsing system shall be removed with top door or
other provisions shall be made such that piping does not interfere with bag
replacement. Connections to compressed air headers and distribution pipes
shall be made with flexible hose with automatic shutoff quick connect
fittings for ease of removal during maintenance. Each row of bags shall be
serviced by its own pulse valve and distribution pipe so that only one row
of bags shall be cleaned per each compressed air pulse. The pulse valves
shall be heavy-duty diaphragm type with solenoid actuators and
stainless-steel internals. Pulse valves shall be designed to limit noise
from pulse valve operation to not more than 84 dBA measured 1 1/2 meters
five feet from the valves. Compressed air and instrument air piping for
SECTION 15864N
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